If you set the right category in the iSlidex settings, and put some posts with images inside that category, it should work.
Please check the FAQ carefully, maybe your issue has already been explained there.
Are you using the regular islidex function [islidex]or the custom one [islidex_custom cat=5 num=3 w=450 h=200 theme=1]?

I checked your site, and first of all you should update wordpress and islidex to their latest version. Second, you should check that the folder /js/cache inside the islidex plugin folder (from FTP) has permission 777.
The slider is fine, it's just not finding any image in the cache folder (for the permission issue), therefore nothing appears.
Please follow instructions and read the faq, and try again.

No, the image must be in each post that goes in the slider.
So write 3-5 posts and put 1 image inside each one of them. Then put these posts in 1 category and set this category inside iSlidex option panel. If you set the /cache folder to 777 the images will automatically be copied there from the posts, and used in the slider.

You MUST: give 777 permission to folder cache inside the islidex plugin folder ->/js/cache
If you don't do that, iSlidex will never work.
Then you must UPLOAD a new image inside your posts, don't put just a link to an image of another post... images must be uploaded inside every post.

This is basic wordpress usage/web development, we can't help you any further with this. Your iSlidex works perfectly fine, we hope you will be able to use it properly, good luck!